I won't do exhibits that have any fees, period. I used to when i was young, and I finally realized that I had spent more money on entry fees than I ever made on sales from these exhibits. Remember too that after charging you to show, these parasites take a HUGE commission if they actually sell anything for you.
I spent 10 years exhibiting my work in the hope of selling some of it, and sold very little. In contrast, my website last year sold more sold more of my work in that one year (a year where the economy sucked!) than I sold in 10 years of showing in better economic times.